Showing papers by "Rui Xu published in 2021"
TL;DR: In this article, the authors explored the adaptability and response of the soil microbiome to As and Sb co-contamination and the impact of cocontamination on microbial metabolic potentials.
92 citations
TL;DR: In this paper, the advantages and challenges of current electrochemical-battery systems involving lithium manganese oxide and lithium iron phosphate systems are reviewed, and the effects of several parameters and relevant mechanisms are discussed, including applied voltage, ionic concentration, pH, time, and coexisting ions.
52 citations
TL;DR: In this article, a facile process for directly regenerating LiFePO4 from spent LFP cathode material involving acid leaching and hydrothermal synthesis is proposed, which can help to avoid the complex element separation process.
45 citations
TL;DR: New insights are provided into taxonomy and potential functions of the root-associated microbiomes of the pioneer plant, M. sinensis, which may facilitate future phytoremediation practices and enrichment of plant-growth promoting functions within the root endosphere were predicted, suggesting theroot endophytes may provide critical services to the host plant.
Abstract: The plant root-associated microbiomes, including both the rhizosphere and the root endosphere microbial community, are considered as a critical extension of the plant genome. Comparing to the well-studied rhizosphere microbiome, the understanding of the root endophytic microbiome is still in its infancy. Miscanthus sinensis is a pioneering plant that could thrive on metal contaminated lands and holds the potential for phytoremediation applications. Characterizing its root-associated microbiome, especially the root endophytic microbiome, could provide pivotal knowledge for phytoremediation of mine tailings. In the current study, M. sinensis residing in two Pb/Zn tailings and one uncontaminated site were collected. The results demonstrated that the metal contaminant fractions exposed strong impacts on the microbial community structures. Their influences on the microbial community, however, gradually decreases from the bulk soil through the rhizosphere soil and finally to the endosphere, which resulting in distinct root endophytic microbial community structures compared to both the bulk and rhizosphere soil. Diverse members affiliated with the order Rhizobiales was identified as the core microbiome residing in the root of M. sinensis. In addition, enrichment of plant-growth promoting functions within the root endosphere were predicted, suggesting the root endophytes may provide critical services to the host plant. The current study provides new insights into taxonomy and potential functions of the root-associated microbiomes of the pioneer plant, M. sinensis, which may facilitate future phytoremediation practices.
43 citations
TL;DR: Results imply that many soil microbes can survival in the Sb/As contaminated sites, and should be promoted to promote the production of safe agricultural products.
40 citations
TL;DR: In this paper, a clean and facile dry process was developed for the preparation of a novel magnetic absorbent by directly milling of enzymatic hydrolysis residues (EHRs) and Fe3O4 nanoparticles together.
31 citations
TL;DR: A new perspective is provided that NPs increase the risk of antibiotic resistance through MGEs during AD process, and ZnO NPs significantly reduced the microbial diversity and significantly changed the microbial community structure.
26 citations
TL;DR: In this paper, a novel process has been developed to strengthen valuable metal recovery from spent lithium-ion batteries by reductive thermal treatment and electrochemical leaching, which can be implemented at room temperature, decreases the application of reducing agent and sulfuric acid, and makes full use of spent graphite.
Abstract: The traditional acid leaching method for recycling valuable metals from the cathode material of spent lithium-ion batteries (LIBs) has encountered the problems of high consumption of H₂SO₄ and reducing agents. In this study, a novel process has been developed to strengthen valuable metal recovery from spent lithium-ion batteries by reductive thermal treatment and electrochemical leaching. With the help of reductive thermal treatment under the conditions of R = 1600 °C and 120 min, the layered structure of the cathode material LiNi₁/₃Co₁/₃Mn₁/₃O₂ is reduced to a mixture of Li₂CO₃, NiO, Co₃O₄, Mn₂O₃, and MnO₂ due to the oxygen releasing from the framework. The destruction of the layered crystal structure reduces the difficulty of leaching valuable metals. 90.59% Ni, 90.53% Co, 66.40% Mn, and 100% Li were leached under the optimal conditions of 20 mL/g liquid–solid ratio, 1.5 M H₂SO₄, 0.8 A, and 150 min at room temperature. Comparing the processes of reductive thermal treatment with acid leaching and direct electrochemical leaching of spent cathode material under the same leaching conditions, the proposed approach can achieve the highest metal recovery and economic benefits. It can be implemented at room temperature, decreases the application of reducing agent and sulfuric acid, and makes full use of spent graphite, resulting in a greener recycling process for recovering valuable metals from spent LIBs.
25 citations
TL;DR: The relative abundance of acidobacteriia correlated positively with the concentrations of arsenic (As), mercury (Hg), chromium (Cr), copper (Cu) and other metals, suggesting their adaptation of the metal-rich environments as discussed by the authors.
Abstract: The relative abundance of Acidobacteriia correlated positively with the concentrations of arsenic (As), mercury (Hg), chromium (Cr), copper (Cu) and other metals, suggesting their adaptation of the metal-rich environments. Metagenomic binning reconstructed 29 high-quality metagenome-assembled genomes (MAGs) associated with Acidobacteriia, providing an opportunity to study their metabolic potentials. These MAGs contained genes to transform As, Hg and Cr through oxidation, reduction, efflux and demethylation, suggesting the potential of Acidobacteriia to transform such metal(loid)s. Additionally, genes associated with alleviation of acidic and metal stress were also detected in these MAGs. Acidobacteriia may have the capabilities to resist or transform metal(loid)s in acidic metal-contaminated sites. Moreover, these genes encoding metal transformation could be also identified in the Acidobacteriia-associated MAGs from five additional metal-contaminated sites across Southwest China, as well as Acidobacteriia-associated reference genomes from the NCBI database, suggesting that the capability of metal transformation may be widespread among Acidobacteriia members. This discovery provides an understanding of metabolic potentials of the Acidobacteriia in acidic metal-rich sites.
24 citations
TL;DR: In this article, the differences in depth-resolved diazotrophic community compositions and interactions in two contrasting sites (to depths of 2m), including a highly contaminated and a moderately contaminated site were compared.
19 citations
TL;DR: In this article, stable isotope probing (SIP) coupled with amplicon and shotgun metagenomic sequencing was used to identify nitrate-dependent Sb(III)-oxidizing bacteria (SbOB) in paddy soils.
Abstract: Antimonite (Sb(III)) oxidation (SbO) can decrease the toxicity of antimony (Sb) and its uptake into rice, thus serving an ecological role in bioremediation of Sb contamination in rice paddies and decreasing the translocation and accumulation of Sb in rice. Nitrate as the electron acceptor can be coupled to SbO in anoxic environments, which, however, has not been reported in paddy soils. Here we investigate the potential for nitrate-dependent SbO in Sb-contaminated rice paddies and identify nitrate-dependent Sb(III)-oxidizing bacteria (SbOB) using stable isotope probing (SIP) coupled with amplicon and shotgun metagenomic sequencing. Anaerobic SbO was exclusively observed in the paddy soil amended with both Sb(III) and NO3−, whereas no apparent SbO was detected in the soil amended with Sb(III) only. The increasing abundance of the arsenite oxidase gene (aioA) suggests that nitrate-dependent SbO was catalysed by microorganisms harbouring the aioA gene. After 60-day DNA-SIP incubation, an obvious shift in the relative abundance of aioA gene to heavy DNA fractions occurred only in the treatment amended with 13C–NaHCO3, Sb(III) and NO3−, suggesting the incorporation of 13C by nitrate-dependent SbOB. Accordingly, a number of putative nitrate-dependent SbOB were identified in the paddy soil, including Azoarcus, Azospira and Chelativorans. Metagenomic analysis further revealed that they contained aioA genes and genes involved in denitrification and carbon fixation, supporting their capability for nitrate-dependent SbO. These observations suggested the occurrence of nitrate-dependent SbO in paddy soils. A number of putative nitrate-dependent SbOB (i.e., Azoarcus, Azospira and Chelativorans) were reported here, which expands our current knowledge regarding the diversity of nitrate-dependent SbOB. In addition, this study provides a proof of concept using DNA-SIP to identify nitrate-dependent SbOB.
TL;DR: It is suggested that Sb contamination might inhibit only AOM but not methane production, and amplicon high-throughput sequencing showed that the Sb addition impaired the diversity of microbial communities and impacted the biotic interactions in the soil.
TL;DR: The combination of DNA-SIP and metagenomic binning provides an opportunity to elucidate the diversity of in situ AOB community inhabiting the activated sludges and provides an understanding of anoxic and/or oxic AOB during the As(III) oxidation process in wastewater treatment facilities, which may contribute to the removal of As from contaminated water.
Abstract: Biological arsenite [As(III)] oxidation is an important process in the removal of toxic arsenic (As) from contaminated water. However, the diversity and metabolic potentials of As(III)-oxidizing bacteria (AOB) responsible for As(III) oxidation in wastewater treatment facilities are not well documented. In this study, two groups of bioreactors inoculated with activated sludge were operated under anoxic or oxic conditions to treat As-containing synthetic wastewater. Batch tests of inoculated sludges from the bioreactors further indicated that microorganisms could use nitrate or oxygen as electron acceptors to stimulate biological As(III) oxidation, suggesting the potentials of this process in wastewater treatment facilities. In addition, DNA-based stable isotope probing (DNA-SIP) was performed to identify the putative AOB in the activated sludge. Bacteria associated with Thiobacillus were identified as nitrate-dependent AOB, while bacteria associated with Hydrogenophaga were identified as aerobic AOB in activated sludge. Metagenomic binning reconstructed a number of high-quality metagenome-assembled genomes (MAGs) associated with the putative AOB. Functional genes encoding As resistance, As(III) oxidation, denitrification, and carbon fixation were identified in these MAGs, suggesting their potentials for chemoautotrophic As(III) oxidation. In addition, the presence of genes encoding secondary metabolite biosynthesis and extracellular polymeric substance metabolism in these MAGs may facilitate the proliferation of these AOB in activated sludge and enhance their capacity for As(III) oxidation. IMPORTANCE AOB play an important role in the removal of toxic arsenic from wastewater. Most of the AOB have been isolated from natural environments. However, knowledge regarding the structure and functional roles of As(III)-oxidizing communities in wastewater treatment facilities is not well documented. The combination of DNA-SIP and metagenomic binning provides an opportunity to elucidate the diversity of in situ AOB community inhabiting the activated sludges. In this study, the putative AOB responsible for As(III) oxidation in wastewater treatment facilities were identified, and their metabolic potentials, including As(III) oxidation, denitrification, carbon fixation, secondary metabolite biosynthesis, and extracellular polymeric substance metabolism, were investigated. This observation provides an understanding of anoxic and/or oxic AOB during the As(III) oxidation process in wastewater treatment facilities, which may contribute to the removal of As from contaminated water.
TL;DR: In this article, two typical PFAS, perfluorooctanoic acid (PFOA) and polyfluoroalkyl substances (PFOS), are selected to investigate their effects on soil microorganisms.
Abstract: The extensive application of perfluoroalkyl and polyfluoroalkyl substances (PFASs) causes their frequent detection in various environments. In this work, two typical PFASs, perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS), are selected to investigate their effects on soil microorganisms. Microbial community structure and microbe–microbe relationships were investigated by high-throughput sequencing and co-occurrence network analysis. Under 90 days of exposure, the alpha-diversity of soil microbial communities was increased with the PFOS treatment, followed by the PFOA treatment. The exposure of PFASs substantially changed the compositions of soil microbial communities, leading to the enrichment of more PFASs-tolerant bacteria, such as Proteobacteria, Burkholderiales, and Rhodocyclales. Comparative co-occurrence networks were constructed to investigate the microbe–microbe interactions under different PFASs treatments. The majority of nodes in the PFOA and PFOS networks were associated with the genus Azospirillum and Hydrogenophaga, respectively. The LEfSe analysis further identified a set of biomarkers in the soil microbial communities, such as Azospirillum, Methyloversatilis, Hydrogenophaga, Pseudoxanthomonas, and Fusibacter. The relative abundances of these biomarkers were also changed by different PFASs treatments. Functional gene prediction suggested that the microbial metabolism processes, such as nucleotide transport and metabolism, cell motility, carbohydrate transport and metabolism, energy production and conversion, and secondary metabolites biosynthesis transport and catabolism, might be inhibited under PFAS exposure, which may further affect soil ecological services.
TL;DR: In this paper, DNA-SIP and metagenomics analysis were combined to identify potential Sb(V)-reducing bacteria and predict their metabolic pathways for Sb (V) reduction.
Abstract: Microorganisms play an important role in altering antimony (Sb) speciation, mobility, and bioavailability, but the understanding of the microorganisms responsible for Sb(V) reduction has been limited. In this study, DNA-stable isotope probing (DNA-SIP) and metagenomics analysis were combined to identify potential Sb(V)-reducing bacteria (SbRB) and predict their metabolic pathways for Sb(V) reduction. Soil slurry cultures inoculated with Sb-contaminated paddy soils from two Sb-contaminated sites demonstrated the capability to reduce Sb(V). DNA-SIP identified bacteria belonging to the genera Pseudomonas and Geobacter as putative SbRB in these two Sb-contaminated sites. In addition, bacteria such as Lysinibacillus and Dechloromonas may potentially participate in Sb(V) reduction. Nearly complete draft genomes of putative SbRB (i.e., Pseudomonas and Geobacter) were obtained, and the genes potentially responsible for arsenic (As) and Sb reduction (i.e., respiratory arsenate reductase (arrA) and antimonate reductase (anrA)) were examined. Notably, bins affiliated with Geobacter contained arrA and anrA genes, supporting our hypothesis that they are putative SbRB. Further, pangenomic analysis indicated that various Geobacter-associated genomes obtained from diverse habitats also contained arrA and anrA genes. In contrast, Pseudomonas may use a predicted DMSO reductase closely related to sbrA (Sb(V) reductase gene) clade II to reduce Sb(V), which may need further experiments to verify. This current work represents a demonstration of using DNA-SIP and metagenomic-binning to identify SbRB and their key genes involved in Sb(V) reduction and provides valuable data sets to link bacterial identities with Sb(V) reduction.
TL;DR: In this article, the authors investigated the active aniline degraders present under contrasting pH environments using three different cultures, namely, acidic sludge (ACID-S, pH 31), neutral river sediment (NEU S, pH 66), and alkaline paddy soil (ALK P, pH 87).
01 Jan 2021
TL;DR: In this article, the authors reviewed the forms, hazards and treatment of phosphorus in wastewater, and focused on the methods of phosphorus-containing wastewater such as chemical precipitation, adsorption, ion exchange, membrane separation and biological methods.
Abstract: In recent years, many rivers, lakes and oceans around the world have exposed to diverse contaminants or red tides due to excessive discharge of nutrients such as nitrogen and phosphorus. The high content of phosphorus often leads to the nutrition of water body. Water resources have been seriously threatened, which has brought great impact on environment and public health. Therefore, the removal of phosphorus from wastewater attracts more and more attention. This work reviewed the forms, hazards and treatment of phosphorus in wastewater, and focuses on the methods of phosphorus-containing wastewater such as chemical precipitation, adsorption, ion exchange, membrane separation and biological methods. With the current economic and development of world, the bio-treatment of phosphorus-containing wastewater will become a research trend in the future, and the research and development of new technologies for phosphorus-containing wastewater will be an important topic for the treatment of phosphorus-containing wastewater in the future.
TL;DR: Results revealed that soils from the SL and GD sites were seriously contaminated by metal(loid)s, including Pb, Zn, As, and Sb, and core microbes, including Halomonas, Pelagibacterium, and Chelativorans played key roles in Cyp plant survival in such harsh environments.
Abstract: Soil contamination due to mining activities is a great concern in China. Although the effects of mining pollution resulting in changes of soil characteristics and the microbiome have been documented, studies on the responses of plant root-associated microbial assemblages remain scarce. In this work, we collected bulk soil, rhizosphere soil, and root endosphere samples of Cyperus rotundus L (Cyp) plants from two Pb/Zn mines, of which, one was abandoned (SL) and the other was active (GD), to investigate the bacterial community responses across different site contamination levels and Cyp plant compartments. For comparison, one unpolluted site (SD) was included. Results revealed that soils from the SL and GD sites were seriously contaminated by metal(loid)s, including Pb, Zn, As, and Sb. Bacterial richness and diversity depended on the sampling site and plant compartment. All sample types from the SL site had the lowest bacterial diversities and their bacterial communities also exhibited distinct patterns compared to GD and SD samples. As for the specific sampling site, bacterial communities from the root endosphere exhibited different patterns from those in bulk and rhizosphere soil. Compared to the GD and SD sites, the root endosphere and the rhizosphere soil from the SL site shared core microbes, including Halomonas, Pelagibacterium, and Chelativorans, suggesting that they play key roles in Cyp plant survival in such harsh environments.
TL;DR: In this article, Sb(III)-oxidizing microcosms were set up using Sb-contaminated rice paddies as inocula and a combination of DNA-SIP and shotgun metagenomic was applied to identify the SbOB and predict their metabolic potential.
TL;DR: In this paper, a solar-driven, self-sustainable electrolytic treatment was conducted in situ to intensify nitrogen and phosphorus removal from eutrophic river water, and the results indicated that the average removal efficiencies of total N and total P under electrolysis conditions reached 72.4 ± 11.7 and 13.8 ± 5.3, respectively.
TL;DR: In this article, the variations of diazotrophic communities in composition and interactions in the mining areas with different extents of arsenic (As) and antimony (Sb) contamination were compared.
Abstract: Nitrogen (N) shortage poses a great challenge to the implementation of in situ bioremediation practices in mining-contaminated sites. Diazotrophs can fix atmospheric N2 into a bioavailable form to plants and microorganisms inhabiting adverse habitats. Increasing numbers of studies mainly focused on the diazotrophic communities in the agroecosystems, while those communities in mining areas are still not well understood. This study compared the variations of diazotrophic communities in composition and interactions in the mining areas with different extents of arsenic (As) and antimony (Sb) contamination. As and Sb co-contamination increased alpha diversities and the abundance of nifH encoding the dinitrogenase reductase, while inhibited the diazotrophic interactions and substantially changed the composition of communities. Based on the multiple lines of evidence (e.g., the enrichment analysis of diazotrophs, microbe-microbe network, and random forest regression), six diazotrophs (e.g., Sinorhizobium, Dechloromonas, Trichormus, Herbaspirillum, Desmonostoc, and Klebsiella) were identified as keystone taxa. Environment-microbe network and random forest prediction demonstrated that these keystone taxa were highly correlated with the As and Sb contamination fractions. All these results imply that the above-mentioned diazotrophs may be resistant to metal(loid)s.
TL;DR: In this article, the enhancing effects of Ag+, ethylenediamine tetraacetic acid (EDTA) and oxalate (Ox) on bio-oxidation of arsenic-bearing gold concentrate and the possible mechanisms were investigated by the leaching experiments, thermodynamic calculation, XRD and SEM analyses.
TL;DR: In this article, the self-assembly behaviors of NaOL, dodecylamine (DDA), and their mixtures in aqueous solution were systematically investigated by large-scale molecular dynamics simulations, respectively.
Abstract: The self-assembly behaviors of sodium oleate (NaOL), dodecylamine (DDA), and their mixtures in aqueous solution were systematically investigated by large-scale molecular dynamics simulations, respectively. The interaction mechanisms between the surfactants, as well as the surfactants and solvent, were revealed via the radial distribution function (RDF), cluster size, solvent-accessible surface area (SASA), hydrogen bond, and non-bond interaction energy. Results showed that the molecules more easily formed aggregates in mixed systems compared to pure systems, indicating higher surface activity. The SASA values of DDA and NaOL decreased significantly after mixing, indicating a tighter aggregation of the mixed surfactants. The RDF results indicated that DDA and NaOL strongly interacted with each other, especially in the mixed system with a 1:1 molar ratio. Compared to van der Waals interactions, electrostatic interactions between the surfactant molecules were the main contributors to the improved aggregation in the mixed systems. Besides, hydrogen bonds were found between NaOL and DDA in the mixed systems. Therefore, the aggregates in the mixed systems were much more compact in comparison with pure systems, which contributed to the reduction of the repulsive force between same molecules. These findings indicated that the mixed NaOL/DDA surfactants had a great potential in application of mineral flotation.
Patent•
09 Feb 2021
TL;DR: In this paper, a biological heavy metal contaminated soil remediation agent as well as a preparation method and application thereof is described, which belongs to the technical field of heavy metal contaminants.
Abstract: The invention provides a biological heavy metal contaminated soil remediation agent as well as a preparation method and application thereof, and belongs to the technical field of heavy metal contaminated soil remediation. The preparation method comprises the steps of inoculating a template material with good stability and dispersibility and iron bacteria into a 9K culture medium, loading the surface and pores of the template material with the iron bacteria so as to add various active groups to the material and enhance the adsorption effect of the template material on metal ions, oxidizing ferrous ions into ferric ions under the action of the iron bacteria at the same time, and after reacting with ammonia water, calcining at high temperature to form the biological heavy metal contaminated soil remediation agent. The remediation agent has the adsorption performance of iron bacteria and iron oxide at the same time and has good dispersing performance. The adopted raw materials are environmentally friendly, the preparation process of the remediation agent is simple, the adsorption efficiency is high, and the effect of remediating soil or water contaminated by heavy metal arsenic and antimony for a long time can be achieved.